Robot for ejection of an object from between two bodies

ABSTRACT

Disclosed is a robot for ejecting an object mounted to a movable body from the movable body, including: a holding section for holding said object mounted on the movable body; and a moving section for ejecting the object from the movable body by movement of the holding section; wherein the moving section includes a first guide section meshing with the holding section for linearly moving the holding section in a first direction by rotation with respect to the action of the movable body; and a second guide section for rotating the holding section in a second direction along with the rotation of the guide section directed in the first direction. The first guide section may be composed of a ball screw, the holding section has a nut, and the ball screw meshes with the nut. Moreover, the second guide means may be composed of a cam and a cam follower meshing with the cam. Additionally, the movable body may be composed of a movable die of a molding machine.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a robot for moving an object from amovable body, and particularly to a robot suitable for ejecting a moldedproduct from dies of a molding machine.

2. Description of the Related Art

The ejectors for ejecting molded products from injection moldingmachines are generally separated into the following two types.

The ejector of the first type starts the ejection of a molded productwhen dies of a molding machine are fully opened. On the contrary, theejector of the second type starts the ejection of a molded productaccording to the opening action of dies of a molding machine by way of amechanical cam.

In the ejector of the first type, however, the ejection takes a longtime because it starts after dies of a molding machine are fully opened.

The ejector of the second type is expected to eject a molded productmore rapidly than the ejector of the first ejector; however, itoccasionally takes a time longer compared with the ejector of the firsttype.

The ejection time described above means a time elapsed between the fullopening and the full closing of dies of a molding machine.

The reason why the ejector of the second type takes a longer time isthat the ejector of this type is suppressed in its moving speeddepending on the magnitude of the power for moving the dies of themolding machine. Moreover, the ejector of the second type has adisadvantage in that it is not stopped directly after dies are stoppedand also not stopped at a specified position because of a large inertiaof the ejector.

Additionally, in the case of changing a cam curve for actuating themechanical cam, the cam must be replaced; accordingly the cam curvecannot be easily changed, which makes it difficult to achieve theoptimization of the ejection.

OBJECT AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a robot capable ofhandling an object such as a molded product for a short time, and ofeasily changing the cam curve according to the ejecting status.

Another object of the present invention is to provide an ejecting robotcapable of simplifying the structure and reducing the weight of theprior art ejecting robots, and of handling an object such as a moldedproduct for a short time; and to provide an ejecting method using theejecting robot.

To achieve the above object, according to the first aspect of thepresent invention, there is provided an industrial robot comprising:opened/closed bodies composed of two members, which are capable of beingopened/closed and contain an object therebetween; a holding means forholding the object; a driving means for moving the holding means in theopening/closing direction of the opened/closed bodies; anadvancing/retracting means which advances/retracts with respect to theopened/closed bodies by turning of the holding means when the holdingmeans is moved in the opening/closing direction of the opened/closedbodies; a position sensor for detecting the positions of theopened/closed bodies; and a control means of receiving the positioninformation of the opened/closed bodies from the position sensor, andcontrolling the drive means for ejecting the object from theopened/closed bodies on the basis of the position information of theopened/closed bodies.

The control means preferably controls the advancing/retracting means tobe moved in the release direction at an approximately maximum speed ofthe advancing/retracting means when the opened/closed bodies are closed.

Moreover, the control means preferably controls the holding means to bemoved in the moving direction of the opened/closed bodies by rotation ofa feed screw, and the advancing/retracting means includes a guide meansfor advancing/retracting with respect to the opened/closed bodies byturning of the holding means when the feed screw is rotated.

Additionally, the opened/closed bodies are preferably composed of diesof a molding machine.

According to the second aspect of the present invention, there isprovided an ejecting method of ejecting an object mounted on a movablebody from the movable body, comprising the steps: meshing a holdingmeans for holding the object mounted on the movable body with a guidemeans directed in a first direction, and rotating the guide meansdirected in the first direction with respect to the action of themovable body, thereby linearly moving the holding means in the firstdirection; and rotating the holding means in a second direction alongwith the rotation of the guide means directed in the first direction,thereby ejecting the object from the movable body.

According to the third aspect of the present invention, there isprovided a robot for ejecting an object mounted to a movable body fromthe movable body, comprising: a holding means for holding the objectmounted on the movable body; and a moving means for ejecting the objectfrom the movable body by movement of the holding means; wherein themoving means includes a first guide means meshing with the holding meansfor linearly moving the holding means in a first direction by rotationwith respect to the action of the movable body; and a second guide meansfor rotating the holding means in a second direction along with therotation of the guide means directed in the first direction.

The first guide means is preferably composed of a ball screw, theholding means has a nut, and the ball screw meshes with the nut.

Moreover, the second guide means is preferably composed of a cam and acam follower meshing with the cam.

Additionally, the movable body is preferably composed of a movable dieof a molding machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a robot and a molding machine according to apreferred embodiment of the present invention;

FIG. 2 is a side view of the molding machine and the robot shown in FIG.1;

FIG. 3 is a development of a cylindrical cam in the robot shown in FIG.1;

FIG. 4 is a view showing an example of a swing angle of a holder of therobot;

FIG. 5 is a view showing an example of the cam length of the cylindricalrobot;

FIG. 6 is a view showing an example of an average gradient of a camgroove of the cylindrical cam;

FIG. 7 shows a flowchart of the method of the embodiment 1 shown inFIGS. 1 and 2;

FIG. 8 is a view showing another flowchart of the embodiment 1 shown inFIGS. 1 and 2;

FIG. 9 is a view for explaining the PTP (point-to-point) control in theaction example 2 shown in FIG. 8;

FIG. 10 is a view showing an arm mechanism of the robot and part of themolding machine according to a preferred embodiment 2 of the presentinvention;

FIG. 11 is a plan view showing the robot of the embodiment and themolding machine shown in FIG. 1;

FIG. 12 is a view showing the interior of the moving means of the robotshown in FIG. 2;

FIG. 13 is a bottom view of the moving means of the robot shown in FIG.2;

FIG. 14 is a sectional view of the moving means of the robot shown inFIG. 2;

FIG. 15 is a view showing the loci of a first arm ring, cam roller andarm head in an arm mechanism;

FIG. 16 is a view showing a flowchart example of the embodiment 2 shownin FIGS. 1 and 6 in comparison with the flowchart example of theconventional robot;

FIG. 17 is a view of the related robot for explaining the improvementmade in a preferred embodiment 3 of the present invention;

FIG. 18 is a view showing a shape of a cam used for the related robot;

FIG. 19 is a view showing the robot and the molding machine according tothe embodiment 3;

FIG. 20 is a side view of the robot and the molding machine of theembodiment 3; and

FIG. 21 is a flow chart showing the method of the embodiment 3 shown inFIGS. 19 and 20.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

Embodiment 1

FIG. 1 is a view showing a robot according to the preferred embodimentof the present invention; and FIG. 2 is a side view of the robot shownin FIG. 1.

A robot 290 shown in FIGS. 1 and 2 is used to eject a molded product Fmolded by an injection molding machine 10.

The injection molding machine 10 will be first described below.

The injection molding machine 10 has heads 12 and 14, which may becalled "dies" or "open/closed bodies". The head 12 is movable in thedirection of the arrow Z by a drive means 300 while holding the moldedproduct F.

The head 14 is fixed, and it is formed with a cavity 16 and a passage 18through which a molding material is poured to the cavity 16.

The molded product F having a disk-like shape or the like can be formedin the cavity 16 between the heads 12 and 14. The molded product F isused for an information recording medium such as an optical disk, andoptical-magnetic disk.

The robot 290 will be described below.

As shown in FIGS. 1 and 2, the robot 290 is generally provided with amoving means 292, position sensor 260 and a controller 220.

The moving means 292 will be described below.

The moving means 292 is adapted to move the molded product F from thehead as the so-called moving body, or to transfer the separated moldedproduct F. The moving means 292 includes a holder 200 removably holdingthe molded product F, connecting arm 201 and a supporting member 202.

The holder 200 is connected to the supporting member 202 by means of theconnecting arm 201. The holder 200 is capable of removably attractingthe molded product F by vacuum attraction.

Moreover, the supporting means 202 of the moving means 292 is rotatablyheld by a nut 206 through a bearing 204, and which is formed into a ringshape or the like. The moving means 292 further includes a drive means294 and advancing/retracting means 296.

The drive means 294 is adapted to move the holder 200 in the directionof the arrow Z. Namely, the drive means 294 includes a motor 208, a ballscrew 207 rotated by the output shaft of the motor 208, and the nut 206.The ball screw 207 is rotated by the drive of the motor 208, to move thenut 206 and the holder 200 integrally in the direction of the arrow Z.

The advancing/retracting means 296 will be described below.

The advancing/retracting means 296 has a guide means 299. The guidemeans 299 includes a cylindrical cam 212 and a cam follower 210. The camfollower 210 is mounted on the outer peripheral surface of thesupporting member 202. As shown in FIGS. 1 and 2, a cam groove 211meshing with the cam follower 210 is formed on the inner surface of thecylindrical cam 212. The cylindrical cam 212 and the motor 208 arepreferably fixed on a base 214.

FIG. 3 shows the development of the cam groove 211 of the cylindricalcam 212. The cam groove 211 has a rotational direction accelerating area236, a rotational direction decelerating area 232 and a final linearlymoving area 234.

As the ball screw 207 is rotated by the drive of the motor 208 shown inFIG. 1, the holder 200 is moved in the direction of the arrow Z, andsimultaneously, as shown in FIG. 2, it is swung by a swing angle θbetween a retracting position P1 and a ejecting position P2.

The swing angle θ is preferably about 90°, as shown in FIG. 4. The camlength L is shown in FIG. 5, which is for example 120 mm. The radius ofthe swing angle θ is for example 35 mm in FIG. 4.

FIG. 6 shows an example of an average gradient of the cam groove 211 ofthe cylindrical cam. The average gradient θ1 is for example 25°.

In addition, a slider 221 shown in FIG. 2 is a rotation preventivemember for preventing the rotation of the nut 206 accompanied with theball screw 207.

Next, a controller 220 and a position sensor 260 will be describedbelow.

The controller 220 is adapted to receive positional information from theposition sensor 260. The position sensor 260 is mounted on the head 12.A rod 270 of the position sensor 260 is fixed on the fixed head 14.Thus, by movement of the movable head 12 in the direction of the arrowZ, it is possible to obtain the position of the movable head 12 relativeto the fixed head 14, that is, the opening degree between the heads 12and 14, as the positional information.

The position sensor 260 is composed of, for example an encoder. On thebasis of the positional information PS from the position sensor 260, thecontroller 220 performs the servo-position control for the motor 208.

Example 1 for Embodiment 1

Next, the method of embodiment 1 will be described below.

FIG. 7 shows a flowchart example 1 having the steps ST1 to ST12.

First, in the step ST1, the heads 12 and 14 of the molding machine 10shown in FIG. 1 are closed. At this time, the cavity 16 is filled withresin, to mold the molded product F.

Next, as the head 12 is started to be opened by a drive means 300 (stepST2), the position sensor 260 shown in FIG. 1 detects positioninformation PS of the head 12, and transmits it to the controller 220.Namely, a pulse of the position information PS is given from theposition sensor 260 composed of the encoder to the controller 220. Thecontroller 220 calculates a target value, that is, a target position towhich the holder 200 is to be moved, by the software on the basis of theencoder value (step ST3).

On the basis of the target value, as shown in FIG. 1, the controller 220transmits a servo-position control signal SS to the motor 208, toperform the servo-position control for the motor 208 (step ST4).

Next, the controller 220 judges whether or not the holder 200 shown inFIG. 1 reaches the molded product F. When judging that the holder 200reaches the molded product F, the controller 220 transmits a command ofejecting the molded product F to the drive means 300 of the injectionmolding machine 10. Thus, the drive means 300 is operated to project apin (not shown) from the movable head 12 of the injection moldingmachine 10, to eject the molded product F from the head 12 (step ST5).

When the controller 220 judges that the holder 200 does not reach themolded product F, the process is returned to the step ST3 again.

In the case that the molded product F is ejected in the step ST6, it isconfirmed whether or not the molded product F is held by the holder 200.If not confirmed, the process is returned to the step ST3. Theconfirmation is made by giving the output of a sensor disposed on theholder 200 to the controller 220.

The detail action of the holder 200 which approaches the molded productF and holds it will be described with reference to FIGS. 1 and 2.

On the basis of the servo-control signal SS from the controller 220, themotor 208 is driven and the ball screw 207 is rotated, so that theholder 200 is started to be moved in the direction of the arrow 2 (leftside of FIG. 1). At this time, the cam follower 210 is guided along thecam groove 211. Thus, as shown in FIG. 2, the holder 200 is started tobe rotated from the retracting position P1 to the ejecting position P2along the rotational direction R1 within the range of the swing angle θ.

First, the holder 200 is, as shown in FIG. 3, rapidly rotated in therotational direction R1 along the rotational direction accelerating area236, and is decelerated in the rotational direction decelerating area232, to be located at the ejecting position P2 shown in FIG. 2. Finally,the holder 200 is moved in the direction of the arrow Z1 shown in FIG. 1in the final linearly moving area 234.

Referring to FIG. 7 again, after the holding of the molded product F bythe holder 200 is confirmed, that is, after the molded product F isvacuum-attracted by the holder 200, the controller 220 transmits asignal to the molding machine 10 (step ST7), to close the head 12 of themolding machine 10 (step STS).

As the head 12 is started to be closed, the positional information PSbeing the encoder value of the position sensor 260 is given to thecontroller 220. The controller 220 calculates, on the basis of theencoder value, a target value corresponding to a target position towhich the holder 200 is to be moved (step ST9).

The controller 220 transmits the servo-position control signal SS to themotor 208, to perform the servo-position control for the motor 208 (stepST10). Thus, the controller 220 judges whether or not the heads 12 and14 of the molding machine 10 are closed (step ST11). When the heads 12and 14 are not closed, the process is returned to the step ST9.

When the controller 220 judges, on the basis of the encoder value fromthe position sensor 260, that the heads 12 and 14 of the molding machine10 are closed, the holder 200 discharges the molded product F attractedthereto to a different location.

Example 2 for Embodiment 1

In a flowchart example 2 shown in FIG. 8, the steps from the step ST1 tothe step ST7 are the same as those from the step ST1 to the step ST7 ofthe flowchart example 1. Accordingly, the description of the actionsfrom the step ST1 to the step ST7 is omitted.

The flowchart example 2 shown in FIG. 8 is different from the flowchartexample 1 in the steps from the step ST20 to the step ST22.

Namely, when it is confirmed that the molded product F shown in FIG. 1is held by the holder 200 (step ST7), the controller 220 transmits asignal to the drive means 300 of the molding machine 10, to close thehead 12 (step ST20).

As the head 12 is started to be closed to the head 14, the holder 200 isreleased at a full speed up to the retracting position P1 as the escapeposition (see FIG. 2) by PTP control. The PTP control is the so-calledpoint-to-point control, and is intended to achieve the full speedrelease irrespective of the path.

As the above-described full speed release by the PTP control, the methodshown in FIG. 9 is adopted. Namely, to prevent the heads 12 and 14 fromapproaching the holder 200 excessively and from being brought in contacttherewith, even in the case that the robot 290 is urgently stopped, theholder 200 is controlled to be retracted from the position between theheads 12 and 14 at a full speed.

Next, the preferred embodiment 2 of the present invention will bedescribed below.

Embodiment 2

FIG. 10 shows part of a robot according to the preferred embodiment 2 ofthe present invention, and heads 12 and 14 of a molding machine 10 usedin combination with the robot 20.

Referring to FIG. 10, of a pair of the head 12 and 14 disposed in themolding machine 10, the head 12 is movable in the direction of Z by adrive means 300. FIG. 10 shows the state that the heads 12 and 14 areopened. The head 14 is formed with a cavity 16, and a passage 18 throughwhich a molding material is supplied to the cavity 16.

The heads 12 and 14 is closed by the movement of the head 12 in thedirection of Z. In the state that the heads 12 and 14 are closed, aresin is supplied from the passage 18 to the cavity 16 between the heads12 and 14, to mold a molded product F having a disk-like shape or thelike.

The molded product F thus molded is used for an information recordingmedium such as an optical disk and optical-magnetic disk. The moldedproduct F can be ejected from the head 12 at a high speed by anattracting means such as an arm mechanism 24 of the robot 20 asdescribed later.

Next, the robot 20 for ejecting the molded product F will be describedbelow.

As shown in FIGS. 11 and 12, the robot 20 has a moving means 400, aposition sensor 260 and a controller 100.

The moving means 400 has a movement operating portion 22 and an armmechanism 24 (or robot arm) moved by the movement operating portion 22for ejecting the molded product F.

Movement Operating Portion 22

First, the moving portion 22 will be described.

FIG. 11 shows the movement operating portion 22, wherein the armmechanism is moved by the movement operating portion 22. The movementoperating portion 22 is adapted to insert an arm head 154 of the armmechanism 24 between the heads 12 and 14 at a speed being two times asmuch as the normal speed, that is, the doubling speed, and to retractthe arm head 154 of the arm mechanism 24 to which the molded product Fis attracted, from the position between the heads 12 and 14.

The movement operating portion 22 has a main body portion 25, and firstand second shaft portions 30 and 40 disposed on the main body portion25. The first and second shaft portions 30 and 40 are disposed inparallel to each other along the direction of the arrow X, as shown inFIGS. 12 to 14.

In particular, as shown in FIG. 12, the first shaft portion 30 of themovement operating portion 22 has a ball screw 32 and a motor 34 capableof rotating the ball screw 32 normally and reversely. The motor 34 ispreferably a servo-motor, and which is mounted on a narrow side surface60 of the main body 25.

As shown in FIG. 12, one end of the ball screw 32 is connected to theoutput shaft of the motor 34, while the other end of the ball screw 32is rotatably supported by a bearing 64 fixed on a base plate 62 of themain body 25. The ball screw 32 shown in FIG. 12 can be rotated normallyand reversely by the drive of the motor 34 shown in FIG. 11 on the basisof a command from the controller 100.

Moreover, as shown in FIG. 12, the ball screw 32 of the first shaftportion 30 meshes with a nut 36. The nut 36 is called the first shaftball screw nut, which can be moved in the direction of the arrow X bythe normal or reversed rotation of the ball screw 32. The nut 36 isconnected or fixed to a first rectangular slide base 70 shown in thetwo-dot chain line. Accordingly, by the normal or reversed rotation ofthe ball screw 32, the nut 36 and the first slide base 70 connected orfixed to the nut 36 are can be linearly moved in the direction of thearrow X along two guides 80 and 80 by the effective stroke of the ballscrew 32.

On the other hand, the second shaft portion 40 shown in FIG. 12 has aball screw 42 and a motor 44 capable of rotating the ball screw 42normally and reversely. The motor 42 is preferably a servo-motor, whichis fixed on the above slide base 70.

As shown in FIG. 12, one end of the ball screw 42 of the second shaftportion 40 is connected to the output shaft of the motor 44; while theother end of the ball screw 42 is rotatably supported by a bearing 74.The bearing 74 is fixed on a slider member 90. The slider member 90 canbe moved in the direction of the arrow X along the guides 80 and 80 justas the above first slide base 70. Thus, the ball screw 42 shown in FIG.12 can be normally and reversely rotated by the drive of the motor 44shown in FIG. 11 on the basis of a command from the controller 100.

Moreover, as shown in FIG. 12, the ball screw 42 of the second shaftportion 40 meshes with a nut 46. The nut 46 is called the second shaftball screw nut, which can be moved in the direction of the arrow X bythe normal and reversed rotation of the ball screw 42. The nut 46 isconnected or fixed to a rectangular slide base 85 shown by the two-dotchain line. Accordingly, the nut 46, and the second slide base 85 andthe slider member 90 connected or fixed to the nut 46 can be linearlymoved along the direction of the arrow X by the effective stroke of theball screw 42 along the two guides 80 and 80 by the normal and reversedrotation of the ball screw 42.

With this construction, the first slide base 70 can be linearly movedfrom the original position P0 by the effective stroke of the ball screw32 of the first shaft portion 30 to the position P1. Moreover, thesecond slide base 85 can be linearly moved from the original position P0by the effective stroke of the ball screw 42 of the second shaft portion40 to the position P2.

Namely, the slide base 85 can be linearly moved from the position P0 tothe position P1 shown in FIG. 3 by the effective stroke of the ballscrew 32 of the first shaft portion 30 and the effective stroke of theball screw 42 of the second shaft portion 40.

At this time, since the first shaft portion 30 and the second shaftportion 40 are simultaneously driven by the controller 100 shown in FIG.11, the second slide base 85 can be linearly moved at the speed of thatof the first shaft portion 30 added with that of the second shaftportion 40, that is, the doubling speed. Thus, as compared with the casethat only one of the first and second shaft portions 30 and 40 isprovided, the second slide base 85 can obtain the doubled moving speed.

Arm Mechanism 24

Next, the arm mechanism 24 will be described with reference to FIG. 11.

In FIG. 11, a base portion 120 of the arm mechanism 24 is connected tothe second slide base 85. In FIG. 11, the solid line in the centralportion shows the state that the arm mechanism 24 is contracted; and thetwo-dot chain line in the left shows the state that it is extended.

Moreover, the main body portion 25 includes a member (not shown), whichis formed with a cam groove 130 for guiding the movement of the armmechanism 24. The cam mechanism 130 has a linear portion 132 formedalong the direction of the arrow X, and a leading edge portion 134directed in the direction crossing that of the arrow X by a specifiedangle. The linear portion 132 and the leading edge portion 134 forms acam curve.

The cam roller 160 on the side of the arm mechanism 24 is adapted to beguided along the cam groove 130. The arm mechanism 24 has a first armlink 150 and a second arm link 152. One end of the first arm link 150and one end of the second arm link 152 are rotatably connected to an armhead 154. Moreover, the other end of the first arm link 150 and theother end of the second arm link 152 are rotatably connected to thesecond slide base 85.

The first arm link 150, second arm link 152, arm head 154 and slide base85 constitute the so-called parallel link. Moreover, a bracket is fixedon the first arm link 150, and the cam roller 160 is mounted to theabove bracket.

In addition, as shown in FIGS. 11 and 13, when the second slide base 85is located at the position P0, the arm mechanism 24 is perfectlycontracted or perfectly escaped, as shown in the central portion of FIG.11. On the other hand, as the slide base 85 advances from the positionP0 to the position P1, the arm mechanism 24 is perfectly extended.

Next, the controller 100 and the position sensor 260 will be described.

The position sensor 260 is, as shown in FIG. 11, mounted on the movablehead 12. The position sensor 260 is composed of, for example an encoder,which is adapted to supply an encoder value obtained by the movement ofthe head 12 to the controller 100 as position information PS.

A drive means 300 of the head 12 can be controlled by the controller100. Namely, the controller 100 controls the drive means 300 to move thehead 12 in the direction of the arrow Z, and to eject the molded productF from the head 12 by the operation of a pin (not shown).

In addition, the motors 34 and 44 are connected to the controller 100.The controller 100 is composed of, for example a standard 4-shaft typecontroller. The motors 34 and 44 are respectively connected to the firstand second shafts of the controller, and the drive means 300 isconnected to the third shaft of the controller 300. Moreover, theposition sensor 260 is connected to the controller 100 as the encoder ofthe drive means 300 of the third shaft.

Example for Embodiment 2

A flowchart example for the embodiment 2 is similar to the flowchartexample 1 of the embodiment 1 shown in FIG. 7.

There will be described steps in which the molded product F of themolding machine 10 is ejected at a high speed by the robot shown in FIG.11.

First, in FIG. 11, the arm mechanism 24 of the robot 20 is perfectlycontracted, as shown by the solid line.

As the heads 12 and 14 of the molding machine 10 shown in FIG. 10 areclosed, the cavity 16 between the heads is filled with resin, to moldthe molded product F.

The head 12 starts to open, to open the cavity 16. As the head 12 isstarted to be opened, the position sensor 260 in FIG. 11 gives positioninformation PS to the controller 100. The controller 100 calculates atarget value corresponding to a target position to which the holder 154of the robot 20 to be moved on the basis of the position information PSas the encoder value.

On the basis of the target value, the controller 100 performs theservo-position control for the motor 34 of the first shaft portion 30and the motor 44 of the second shaft portion 40 shown in FIG. 11, sothat the motor 34 of the first shaft portion 30 and the motor 44 of thesecond shaft 40 are normally rotated. Thus, the second slide base 85advances from the position P0 to the position P1 shown in FIG. 11.

Along with the movement of the second slide base 85, the arm mechanism24 is shifted to the state that it is perfectly contracted and the statethat it is perfectly extended. Namely, the first arm link 150 and thesecond arm link 152 of the arm mechanism 24 are restricted by theconfiguration of the cam groove 130 through the cam roller 160. As shownin FIG. 15, they are moved in the directions of the arrows X and Z whiledepicting the locus shown in FIG. 15.

Namely, by the operation of the arm mechanism 24 shown in FIG. 11, thearm head (or holder) 154 is moved in the direction of the arrow X shownin FIG. 15 while the cam roller 160 is moved along the linear lineportion 132 of the cam groove 130. FIG. 15 shows a locus RT of the camroller, a locus RT of the first arm link and a locus of the arm head154. Moreover, the arm head 154 is moved in the synthesizing directionof the arrows X and Z shown in FIG. 15 during the cam roller 160 shownin FIG. 16 is moved along the leading edge portion 134 of the cam groove130, and is finally directed to the head 12 along a central axis L ofthe head 12.

Thus, the arm head 154 shown in FIG. 11 advances between the heads 12and 14, and reaches the molded product F. The molded product F ispreferably attracted and chucked by a vacuum attracting means (notshown).

As the head 12 of the molding machine 1 is started to be closed afterconfirmation of the holding of the molded product F, the controller 100calculates a target value corresponding to a target position to whichthe holder 154 is to relocate on the basis of the position informationPS of the position of the head 12 from the position sensor 260.

The controller 100 performs the servo-position control for the motors 33and 44 according to the target value, and reversely to theabove-described case, the cam roller 160 is moved along the linear lineportion 132 from the leading edge portion 134, so that the arm head 154is released between the heads 12 and 14 while holding the molded productF, to be thus returned to the perfect contracted state.

After the heads 12 and 14 of the molding machine 10 are closed, thecontroller 100 gives a signal to eject the molded product F from theholder 154.

In addition, in such an action, when being escaped, the arm head 154 maybe released from the position between the heads 12 and 14 at a fullspeed using the PTP control described in FIG. 8.

The method of operating the movement of the arm mechanism 24 is shown inFIG. 16.

In FIG. 16, the movement of the arm head in the conventional robot isalso shown for comparison. As is apparent from FIG. 16, the embodimentof the present invention can eject the molded product from the moldingmachine for a period of time being approximately half compared with theconventional example. In addition, FIG. 16 shows the action examples forthe robot and the molding machine in the embodiment of the presentinvention, and the conventional example.

According to the embodiment of the present invention, the first andsecond shaft portions of the movement operating portion 22 are directedin the same direction; accordingly, the arm mechanism 24 can eject themolded product from the molding machine at a doubling speed of themovement operating portion 22 or at the further high speed by theboosting mechanism, thereby enhancing the tact time of the moldingmachine.

In the case that a doubled speed, twice the conventional speed, isrequired by the conventional X-Y robot, the construction of the robotincluding the controller must be largely changed in terms of the powerof the motor, danger speed of the ball screw and the life of the guide;accordingly, the size of the X-Y robot is enlarged.

Moreover, according to the embodiment 2 of the present invention, therobot 20 capable of ejecting the molded product at a full speed iscombined with the arm head 154 capable of moving in the Z direction, sothat it is possible to operate the robot 20 directly after the openingof the cavity of the molding machine. On the contrary, the conventionalrobot is short in stroke or large in the size of the unit of the drivesource, so that the robot cannot be operated unless the cavity isperfectly opened.

Moreover, in the embodiment 2, it is possible to close the cavity of themolding machine directly after the molded product is ejected by therobot. On the contrary, in the conventional robot, the cavity cannot beclosed after the molded product is perfectly ejected.

Thus, the embodiment of the present invention makes it possible tominimize the loss time for ejection of the molded product, and toshorten the cycle time.

The present invention is not limited to the above embodiment.

The robot according to the embodiment of the present invention may beapplied to the work of mounting or removing parts to or from the moldingmachine or the other machine, other than the ejection of the moldedproduct of the molding machine. In the above embodiment, the armmechanism can be moved at the doubled speed by the movement operatingportion.

However, in the robot of the embodiment 2, the movement operatingportion may be constituted of three motors, three ball screws and threenuts, to be moved at a tripled speed. Furthermore, the arm mechanism maybe moved at the tripled speed or more.

Moreover, the X-direction as the first direction is not necessarilycrossed at right angles to the Z-direction as the second direction. Thismay be variously changed according to the apparatus using the robot ofthe present invention.

Moreover, in the embodiments 1 and 2, in the case that the moldedproduct F is a compact disk molded from the head (die) of the moldingmachine, the molded product can be attracted and ejected incorrespondence with the movement of the head (die). Namely, since themolded product is not ejected using the power for moving the dies as inthe conventional robot, the acceleration in moving the holder is notrestricted depending on the power for moving the dies.

Additionally, in the embodiments 1 and 2, the molded product is notejected by the mechanical cam; but is ejected using the software systemin which the position information corresponding to the movement of theheads (dies) of the molding machine is transmitted to the controller forcontrolling the ejection of the molded product on the basis of theposition information.

The controller is adapted to control the holder or arm head at thetarget position determined by the opening degree of the die indicated bythe position information transmitted from the position sensor such asthe encoder.

The target position can be easily changed by the program of thecontroller. Accordingly, only by the slight change of the software ofthe controller, the movement of the movable body such as a die in theuser program can be grasped without the change of the mechanicalportion. Moreover, inexpensive, simple and standard program andequipment can be used.

Accordingly, the software system can be easily changed in the controlleraccording to the usage. As a result, it is possible to eject the moldedproduct F from the heads in a short amount of time.

For example, in the injection molding for the conventional compact disk,the cycle time takes 5.8 sec and the ejecting time takes 1.6 sec; whilein the embodiment 1 of the present invention, the ejecting time isshortened to be 0.8 sec. Since the ejecting time is shortened from the1.6 sec to 0.8 sec, the whole cycle time can be shortened from 5.8 secto 5.0 sec, which makes it possible to enhance the productivity by about16%.

As described above, according to the present invention, an object suchas a molded product can be removed from a movable body according to themovement of the movable body such as a die of a molding machine.Accordingly, differently from the conventional system in which theobject is moved using the power for the movable body, there is nolimitation to the magnitude of the power for moving the movable body,and no limitation to the speed at which the object is moved from themovable body. This makes it possible to move the object from the movablebody in a very short time.

Moreover, since the system of the present invention does not use thepower for moving the movable body such as a die to the movement of theobject through the mechanical cam, the movement of the movable body isfreely varied without the change in the mechanical cam.

Embodiment 3

(1) Function

An injection molding machine includes a movable die and a fixed die. Amolded product molded between the movable die and the fixed die isejected from the movable die by an ejector constituted of a robot whenthe movable die is separated from the fixed die.

Concretely, the ejector of this kind includes a swing type arm forremovably holding a molded product. When the movable die is separatedfrom the fixed die to eject the molded product, the swing type arm isswung or rotated and is inserted between the movable die and he fixeddie for holding the molded product, after which it is swung in thereversed direction to eject the molded product from the position betweenthe movable die and the fixed die.

The ejectors described above include the following systems, each ofwhich has a disadvantage.

(1) In the system in which the swing type arm is provided on the movabledie, since the weight of the swing type arm is added with the weight ofthe movable die, it is difficult to move the movable die at a high speedwhen the molded product is ejected. Moreover, because of the largeweight, the accuracy in stopping the movable die is poor, which exertsadverse effect on the accuracy in the dimension of the product, andshortens the life of the molding machine.

(2) In the system in which the swing type arm is provided on the movabledie (Marchin system), a swing type arm 400 is swung in the direction ofthe arrow R shown in FIG. 17. The swing is performed by guiding of thecam groove 450 of a cylindrical cam 440 shown in FIG. 18.

In the system in which the swing type arm is fixed in the movable die,the total weight Wt applied to the movable die is expressed by thefollowing equation.

    Wt=We+W1+W2                                                (1)

where We indicates an equivalent weight of the swing type arm 400 shownin FIG. 17 when it is swung; and W1 indicates the weight of a moldedproduct holding portion 410 of the swing type arm 400; and W2 is theweight of a base portion 420 of the swing type arm 400.

The equivalent weight we of the above swing type arm 400 in the Marchinsystem due to swing is calculated as follows.

First, an inertia moment I is calculated by the following equation.

    I=1/2·W2/g·(dl/2).sup.2 ·(W1/g)l(2)

where l is the length of the arm 400 and the dl is the diameter of thebase portion 420.

Next, the kinetic energy T is calculated by the following equation.

    T=1/2·Iθ.sup.2 =1/2·I (df/dx·x).sup.2 =1/2·I (df/dx).sup.2 ·x.sup.2 =1/2·Me·x.sup.2                         (3)

In the equation 3, the cam function of the cylindrical cam 440 isexpressed by θ=f(x), as shown in FIG. 18.

Moreover, Me indicates the weight of the swing type arm 400 convertedinto the linear motion. The weight Me of the swing type arm 400converted into the linear motion is expressed by the following equation.

    Me=I(df/dx).sup.2 (where, df/dx=θ1/l2)=I (θ1/l2).sup.2(4)

Thus, the equivalent weight We of the arm upon swing action is expressedby the following equation.

    We=Meg=I (θ1/l2).sup.2 g                             (5)

where θ1 indicates the cam guide angle of the cam groove 450 of thecylindrical cam 440. The cam groove guide angle θ1 is 90°.

The total weight Wt applied with the movable die including theequivalent weight We can be obtained by the equation 1.

In the system of (2), there is generated the added weight which isequivalent to that applied to the movable die by the swing action, andhas a disadvantage in making if difficult to move the movable die athigh speed just as in the system of (1).

(3) In the system shown in the embodiment 1, in FIG. 2, the flange 202of the swing type arm 201 is rotatably supported by the nut 206 throughthe bearing 204. Namely, the flange 202 of the swing type arm 201 isindirectly set to the nut 206 through the bearing 204.

The nut 206 meshes with the ball screw 207, and can be moved by therotation of the ball screw 207 through the drive of the motor 208.

When the nut 206 is moved, the cam follower 210 of the flange 202 isguided along the cam groove 211 of the cylindrical cam 212 as shown inFIG. 3, to swing the swing type arm 201. Moreover, the nut 206 is fixedon the slider 221, which is guided by the slider guide 222. By theeffect of the slider 221 and the slider guide 222, the nut 206 can keepthe constant angle irrespective of the rotation of the ball screw 07.

Accordingly, the cam follower 210 is guided along the cam groove 211, sothat the wing arm 201 is swung as shown in FIG. 2, and the ejecting head292 of the swing arm 201 ejects the molded product from the movable die12.

In this system, to shorten the time required for ejection of the moldedproduct, it is desirable to insert the ejecting head 292 between themovable die and the fixed die during the opening of the movable die 12.However, in this system, since the pressure angle from the cylindricalcam 214 to the cam follower 210 is made smaller, the rotational speed ofthe ejecting head 292 cannot be increased, so that the ejecting head 292cannot be early inserted between the movable die and the fixed die.

Moreover, this system has the bearing 204 which is large in the size,complex in the structure, and heavy in weight, thereby making itimpossible to handle the molded product for a short time.

The embodiment 3 is made for improving the above problems.

(2) Example

An ejecting robot 590 shown in FIGS. 19 and 20 is used for ejecting amolded product F molded in an injection molding machine 510 in thisexample.

First, the injection molding machine 510 will be described.

The injection molding machine 510 has a movable disk 512 and a fixeddisk 514. The movable disk 512 includes a movable die 502, and the fixeddisk 514 includes a fixed die 504. The movable disk 512 is movable inthe first direction of the arrow Z by a drive means 630.

On the other hand, the fixed die 504 is formed with a passage (notshown), through which the material to be molded is poured in a cavity516 between the movable die 502 and the fixed die 504.

The molded product F includes a disk-like molded product, for example arotational type information recording medium such as an optical disk andoptical-magnetic disk.

Next, the ejecting robot 590 will be described.

As shown in FIGS. 19 and 20, the ejecting robot 590 includes an ejectingarm 600 as a holding means for removably holding the molded product F, amoving means 592 for ejecting the molded product F from the movable die502 of the molding machine 510 by movement of the ejecting arm 600, aposition sensor 516 for detecting the position of the movable disk 512,and a controller 520.

First, the ejecting arm 600 will be described.

As shown in FIGS. 19 and 20, the ejecting arm 600 includes a nut 550, abase portion 601, an extension portion 602, and an ejecting head 604.

As shown in FIG. 20, the extension portion 602 is formed on the baseportion to be tilted at specified angles.

The leading edge portion of the extension portion 602 includes anejecting head 604 removably holding the molded product F. The ejectinghead 604 is adapted to removably hold the molded product F by vacuumattraction.

Moreover, the base portion 601 is directly fixed on the nut 550. The nut550 meshes with a ball screw 545 as described later.

Next, the moving means 592 will be described.

As shown in FIGS. 19 and 20, the moving means 592 is adapted to move themolded product F from the movable die 502 or to remove the moldedproduct F and transfer it to the different location.

The moving means 592 includes a drive portion 610. The drive portion 610is driven to linearly move the ejecting arm 600 along the firstdirection of the arrow Z and move it while swinging or rotating in thesecond direction of the arrow E.

As shown in FIG. 19, the moving means 592 moves the ejecting arm 600 inthe Z direction (first direction) by a specified stroke S; while asshown in FIG. 20, the moving means 92 swings or rotates the ejecting arm600 in the rotational direction (second direction) by a specified swingangle α.

Thus, the moving means 592 linearly moves the ejecting arm 600 in thefirst direction of the arrow Z, and rotates it in the second directionof the arrow E, to eject the molded product F from the movable die 2.

The drive portion 610 of the moving means 592 has the followingconstruction.

A pulley 542 is fixed around an output shaft 541 of a motor 540, and abelt 544 is set between the pulley and another pulley 543.

The pulley 543 is connected to the ball screw 545, which can be rotatedin the direction of the arrow R by the drive of the motor 540.

The ball screw 545 is rotated counterclockwise from the left end of theball screw 545.

The one end and the other end of the ball screw 545 are respectivelysupported by supporting members 546, and 547.

As shown in FIG. 19, the nut 550 of the ejecting arm 600 holding meansdirectly meshes with the ball screw 545. The ball screw 545 functions asa first guide means for directly moving the ejecting arm 600 and the nut550 along the first direction of the arrow Z.

The base portion 601 of the above ejecting arm 600 is fixed on the nut550. Moreover, a supporting member 552 is fixed on the nut 550, and acam follower 554 is set on the supporting member 552.

A cylindrical cam 560 is disposed to be in parallel to the ball screw545. A cam groove 562 is formed on the cylindrical cam 560.

The cam follower 554 is guided in the cam groove 562. The cam groove 562has a first cam groove guide portion 570 and a second cam groove guideportion 572, as shown in FIG. 19.

As shown in FIG. 19, the first cam groove guide portion 570 is formed tobe directed leftward, tiltingly and downwardly. Moreover, the second camgroove guide portion 572 is, as shown in FIG. 19, is formed to be in thehorizontal direction or the direction parallel to the ball screw 545.

The first cam groove guide portion 570 is smoothly connected to thesecond cam groove guide portion 572. The cylindrical cam 560 and the camfollower 554 constitute a second guide means for guiding the ejectingarm 600 and the nut 550 by moving them along the second direction of thearrow E.

The above position sensor 516 is adapted to detect the linear positionsuch as a linear encoder. Namely, the position sensor 516 can detect theposition of the movable die 502 relative to the fixed die 504.

The controller 520 is connected to the drive means 630 of the movabledisk 512 and the motor 540, to control the drive means 630 and the motor540. Moreover, the position sensor 516 is connected to the controller520, to give the position information of the movable die 502 obtained bythe position sensor 516 to the controller 520.

Example of Embodiment 3

Next, the flowchart example of the third embodiment will be described byway of the steps ST1 to ST12 of the flowchart shown in FIG. 21.

First, in the step ST1, the movable disk 512 and the fixed disk 514shown in FIG. 19 are closed. At this time, the cavity is filled withresin, to mold the molded product F.

When the movable disk 512 and the fixed disk 514 are closed, theejecting arm 600 is located at a position A as an initial position shownin the two-dot chain line, as shown in FIGS. 19 and 20. In this initialstate, the cam follower 554 shown in FIG. 19 is located at the first camgroove guide portion 570 of the cam groove 562.

As the drive means 630 is driven on the basis of the command of thecontroller 520, the movable disk 512 is started to be separated from thefixed disk 514 (step ST2). When the movable disk 512 is separated fromthe fixed disk 514, the position sensor 516 transmits the pulse of theencoder value. Accordingly, the controller 520 receives the encodervalue as the position information of the movable disk 512 from theposition sensor 516.

Meanwhile, on the basis of the command of the controller 520, the motor540 is driven simultaneously or differently from the drive of the drivemeans 630, and the rotational force of the motor 540 is transmitted tothe ball screw 545 through the two pulleys 542 and 543 and the belt 544,so that the ball screw 545 is rotated in the direction of the arrow Rshown in FIG. 19.

The controller 520 calculates a target value as a target position towhich the ejecting arm 600 is to be moved, on the basis of the positioninformation of the movable die 502 detected by the position sensor 516.

On the basis of the target value, the controller 520 gives theservo-control signal to the motor 540, to perform the servo-controldrive for the motor 540 by the rotational angle corresponding to thetarget value (step ST4).

By the servo-control drive of the motor 540, the ball screw 545 isrotated in the direction of the arrow R shown in FIG. 19. Accordingly,the ejecting arm 600 and the nut 552 are moved along the left directionas the first direction of the arrow Z and advance from the position A tothe position B. At the same time the ejecting arm 600 and the nut 522are rotated in the position B from the state of the position A along theclockwise direction as the second direction of the arrow E shown in FIG.20.

At this time, the cam follower 554 is moved from the first cam grooveguide portion 570 shown in FIG. 19 to the second groove guide portion572 through the connection portion 573. Namely, in FIG. 19, the camfollower 554 is moved from the right and upper portion to the left anddown portion.

The cam follower 554 is inserted in the second cam groove guide portion572 through the connection portion 573, and then the ejecting arm 600and the nut 550 are only moved in the left direction as the firstdirection shown in FIG. 19 while not being swung or rotated; and theejecting arm 600 and the nut 550 are moved to the position C shown inFIG. 19.

After that, when the ejecting head 604 approaches the movable die 502 asshown in FIG. 19 and is brought in contact with the molded product F(step ST5), an ejection pin (not shown) is acted to eject the moldedproduct F from the movable die 502 (step ST6).

When the ejecting head 604 does not approach the molded product F, theprocess is returned to the step ST3.

The ejected molded product F is attracted and held on the side of theejecting head 504 (step ST7).

When it is confirmed that the molded product F is attracted and held onthe side of the ejecting head 604, the controller 520 gives a signal tothe drive means 630, and the movable disk 512 is moved to the side ofthe fixed disk 514, to close the molding machine 510 (step STS).

As the movable disk 512 is moved on the side of the fixed disk 514 toclose the molding machine 510, the position information of the movabledisk 512 as the encoder value is given to the controller 520 from theposition sensor 516.

The controller 520 calculates a target value corresponding to a targetposition to which the mounting arm 604 and the nut 55 are to be moved onthe basis of the position information (step ST9). The controller 520gives the servo-position control signal to the drive means 630, andperforms the servo-position control for the motor 540 (step ST10).

As the motor 540 is reversely rotated on the basis of the servo-positioncontrol signal, the mounting arm 600 and the nut 550 act in the mannerreversed to the above process. Namely, the cam follower 554 shown inFIG. 19 is moved in the first cam groove guide portion 570 from thesecond cam groove guide portion 572 through the connection portion 573.Namely, in FIG. 19, the cam follower 554 is moved from the left and downportion to the right and upper portion.

While the cam follower 554 is guided by the second cam groove guideportion 572, the mounting arm 600 is moved only in the right directionshown in FIG. 19 while not being swung or rotated.

As the cam follower 554 is guided by the second cam groove guide portion572, the ejecting arm 600 is further moved in the right direction shownin FIG. 19, and is simultaneously rotated from the position B to theposition A shown in FIGS. 19 and 20.

Thus, the ejecting head 604 of the ejecting arm 600 is moved from theposition between the movable die 502 and the fixed die 504 while holdingthe molded product F, and the ejecting arm 600 reaches the position A.

As the movable disk 512 of the molding machine 510 is closed (stepST11), the molded product F is ejected and discharged from the arm 600(step ST12), thus completing the continuous ejecting actions.

According to the embodiment of the present invention, the so-calledejecting arm 600 is fixed directly on the ball screw 545 or the nut 550screwed to the ball screw 545. Accordingly, the direction of the forceapplied to the cam groove guide portion 570 by the cam follower 554(hereinafter, referred to as pressure angle) is not only the firstdirection of the arrow Z as conventional, but also the rotationaldirection R of a force of the ball screw 550, so that the ejecting arm600 can be largely swung even when the movement in the first directionof the arrow Z is small so long as the component of the force in therotational direction R corresponds to the advance direction of the camfollower 554.

Accordingly, to correspond the component of the force in the rotationaldirection R to the advance direction of the cam follower 554, therotational direction R of the ejecting arm 600 is adjusted in thedirection of the screwing rotational advance of the screw groove of theball screw 50 (hereinafter, referred to as turning), in viewpoint of theoverlapping portion of the rotational action and the linear action inthe direction of the arrow Z of the ejecting arm 600.

Concretely, in the case that the arm 600 is turned rightwardly from thelinear advance direction Z, the screw groove of the ball screw 545 isformed in the right ward turning direction; while in the case that thearm 600 is leftwardly turned from the linear advance direction Z, thescrew groove of the ball screw 545 is formed in the leftward turningdirection.

After the molding machine has just started to be opened, the ejectinghead can be inserted between the movable die and the fixed die, andfollow the linear action of the movable die.

Even during the opening of the dies, the ejecting motion for the moldedproduct is possible, and the time required for ejection in the cycle ofthe injection molding can be shortened, resulting in the increasedproductivity.

Since the power of the rotational motion and the linear motion can beobtained using one ball screw, the structure can be simplified with highreliability.

In the system shown in the description of the function of thisembodiment, since a problem is present in the pressure angle between thecylindrical cam and the cam follower, it is difficult to cause theejecting head to be inserted in the dies in the early stage of theopening of the dies.

On the contrary, the third embodiment of the present invention, it ispossible to insert the ejecting head in the very early stage.

The reason for this is that, as described above, the pressure anglebetween the cylindrical cam and the cam follower is small and is notrestricted, and further the ejecting arm can be largely swung even whenthe movement in the first direction is small, so that it is possible toshorten the interval of the linear motion when the ejecting arm isswung.

Moreover, as shown in the first embodiment, the robot does not requirethe bearing, and further does not require the slider and the sliderguide for holding the nut at the constant angle irrespective of therotation of the ball screw. Accordingly, it is possible to simplify thestructure of the robot, to reduce the weight, and to make small thesize.

The present invention is not limited to the above embodiments.

For example, the present invention may be applied to the ejection ofanother object different from the molded product.

The first guide means is not limited to the ball screw, and the shape ofthe cam groove of the cylindrical cam constituting the second guidemeans can be freely selected.

As described above, according to the embodiments of the presentinvention, it is possible to eliminate the necessity of using thebearing, to simplify the structure and reduce the weight, and to handlethe object such as the molded product for a short period of time.

What is claimed is:
 1. An industrial robot comprising:opened/closedbodies composed of two members, which are capable of being opened/closedand which contain an object therebetween; a holding means locatedproximate to said two members for holding said object when said twobodies are opened; a driving means for linearly moving said holdingmeans in an opening/closing direction of said opened/closed bodies; anadvancing/retracting means which advances/retracts in a releasedirection with respect to said opened/closed bodies by turning of saidholding means when said holding means is moved in the opening/closingdirection of said opened/closed bodies; a position sensor, mountedproximate to at least one of said two members, for detecting thepositions of said opened/closed bodies; and a control means forreceiving position information of said opened/closed bodies from saidposition sensor, and controlling said driving means for ejecting saidobject from said opened/closed bodies on the basis of the positioninformation of said opened/closed bodies.
 2. An industrial robotaccording to claim 1, wherein said control means controls saidadvancing/retracting means to be moved in the release direction at anapproximately maximum speed of said advancing/retracting means when saidopened/closed bodies are closed.
 3. An industrial robot according toclaim 2, wherein said control means controls said holding means to bemoved in the opening/closing direction of said opened/closed bodies byrotation of a feed screw, and said advancing/retracting means includes aguide means for advancing/retracting with respect to said opened/closedbodies by turning of said holding means when said feed screw is rotated.4. An industrial robot according to claim 1, wherein said control meanscontrols said holding means to be moved in the opening/closing directionof said opened/closed bodies by rotation of a feed screw, and saidadvancing/retracting means includes a guide means foradvancing/retracting with respect to said opened/closed bodies byturning of said holding means when said feed screw is rotated.
 5. Anindustrial robot according to claim 1, wherein said opened/closed bodiesare composed of dies of a molding machine.
 6. A robot for ejecting anobject mounted on a movable body from said movable body,comprising:opened/closed bodies composed of said movable body and anon-movable body; a holding means located proximate to saidopened/closed bodies for holding said object mounted on said movablebody when said two bodies are opened; and a moving means for ejectingsaid object from said movable body by movement of said holding means;wherein said moving means includes a first guide means meshing with saidholding means for linearly moving said holding means in a firstdirection by rotation with respect to a position of said movable body;and a second guide means for rotating said holding means in a seconddirection while said first guide means is rotated directed in said firstdirection.
 7. A robot according to claim 6, wherein said first guidemeans is composed of a ball screw, said holding means has a nut, andsaid ball screw meshes with said nut.
 8. A robot according to claim 6,wherein said second guide means is composed of a cam and a cam followermeshing with said cam.
 9. A robot according to claim 6, wherein saidmovable body is composed of a movable die of a molding machine.
 10. Anindustrial robot comprising:opened/closed dies of a molding machiningcomposed of two dies, which are capable of being opened/closed and whichcontain an object therebetween; a holding means located proximate tosaid two dies for holding said object when said two dies are opened; adriving means for linearly moving said holding means in anopening/closing direction of said opened/closed dies; anadvancing/retracting means which advances/retracts in a releasedirection with respect to said opened/closed dies by turning of saidholding means when said holding means is moved in the opening/closingdirection of said opened/closed dies; a position sensor, mountedrelative to at least one of said two dies, for detecting the positionsof said opened/closed dies; and a control means for receiving positioninformation related to said opened/closed dies from said positionsensor, and controlling said driving means for ejecting said object fromsaid opened/closed dies on the basis of the position information of saidopened/closed dies.
 11. An industrial robot according to claim 10,wherein said control means controls said advancing/retracting means tobe moved in the release direction at an approximately maximum speed ofsaid advancing/retracting means when said opened/closed dies are closed.12. An industrial robot according to claim 11, wherein said controlmeans controls said holding means to be moved in the opening/closingdirection of said opened/closed dies by rotation of a feed screw, andsaid advancing/retracting means includes a guide means foradvancing/retracting with respect to said opened/closed dies by turningof said holding means when said feed screw is rotated.
 13. An industrialrobot according to claim 10, wherein said control means controls saidholding means to be moved in the opening/closing direction of saidopened/closed dies by rotation of a feed screw, and saidadvancing/retracting means includes a guide means foradvancing/retracting with respect to said opened/closed dies by turningof said holding means when said feed screw is rotated.
 14. A robot forejecting an object mounted on a movable die of a molding machine fromsaid movable die, comprising:opened/closed dies of a molding machinecomposed of said movable die and a non-movable die; a holding meanslocated relative to said opened/closed dies for holding said objectmounted on said movable die when said two dies are opened; and a movingmeans for ejecting said object from said movable die by movement of saidholding means; wherein said moving means includes a first guide meansmeshing with said holding means for linearly moving said holding meansin a first direction by rotation with respect to a position of saidmovable die; and a second guide means for rotating said holding means ina second direction while said first guide means is rotated directed insaid first direction.
 15. A robot according to claim 14, wherein saidfirst guide means is composed of a ball screw, said holding means has anut, and said ball screw meshes with said nut.
 16. A robot according toclaim 14, wherein said second guide means is composed of a cam and a camfollower meshing with said cam.